	US 12,454,735 B2
	Grain-oriented electrical steel sheet, finish annealing-use steel sheet, annealing separator, method for manufacturing grain-oriented electrical steel sheet, and method for manufacturing finish annealing-use steel sheet
Ryutaro Yamagata, Tokyo (JP); Nobusato Morishige, Tokyo (JP); and Ichiro Tanaka, Tokyo (JP)
Assigned to NIPPON STEEL CORPORATION, Tokyo (JP)
Filed by NIPPON STEEL CORPORATION, Tokyo (JP)
Filed on Sep. 2, 2022, as Appl. No. 17/901,936.
Application 17/901,936 is a continuation in part of application No. 17/421,338, abandoned, previously published as PCT/JP2020/000337, filed on Jan. 8, 2020.
Claims priority of application No. 2019-001158 (JP), filed on Jan. 8, 2019.
Prior Publication US 2023/0002849 A1, Jan. 5, 2023
This patent is subject to a terminal disclaimer.
Int. Cl. C21D 9/46 (2006.01); C21D 6/00 (2006.01); C21D 8/12 (2006.01); C22C 38/00 (2006.01); C22C 38/02 (2006.01); C22C 38/04 (2006.01); C22C 38/06 (2006.01); C22C 38/16 (2006.01); C22C 38/60 (2006.01); H01F 1/147 (2006.01)

CPC C21D 9/46 (2013.01) [C21D 6/005 (2013.01); C21D 6/008 (2013.01); C21D 8/1222 (2013.01); C21D 8/1233 (2013.01); C21D 8/1255 (2013.01); C21D 8/1283 (2013.01); C22C 38/001 (2013.01); C22C 38/002 (2013.01); C22C 38/008 (2013.01); C22C 38/02 (2013.01); C22C 38/04 (2013.01); C22C 38/06 (2013.01); C22C 38/16 (2013.01); C22C 38/60 (2013.01); H01F 1/14775 (2013.01); C22C 2202/02 (2013.01)]

2 Claims

1. A grain-oriented electrical steel sheet comprising

a base steel sheet having a chemical composition comprising, by mass %,

C: 0.0050% or less,

Si: 2.5 to 4.5%,

Mn: 0.02 to 0.20%,

one or more elements of S and Se: total of 0.005% or less,

sol. Al: 0.010% or less, and

N: 0.010% or less and

having a balance comprised of Fe and impurities and

a primary coating formed on a surface of the base steel sheet and comprising 50 mass % or more of Mg₂SiO₄, where,

uneven-shape information of a surface of the primary coating when designating a direction from a primary coating side toward the base steel sheet in a thickness direction of the base steel sheet as positive is laid out projected on a plane parallel to the surface of the steel sheet,

when designating a center value of a surface height of the primary coating as H0, the primary coating existing at the base steel sheet side from H0+0.2 μm is prescribed as an “anchoring oxide layer region” and the primary coating existing at the primary coating side from H0+0.2 μm is prescribed as a “surface oxide layer region”, and,

in a correlation distribution chart of a characteristic X-ray intensity laying out constituent information in the primary coating projected on the plane parallel to the surface of the steel sheet and uneven shape, a maximum value of the characteristic X-ray intensity of Al is identified and a region where a characteristic X-ray intensity of Al is 20% or more of the maximum value of the characteristic X-ray intensity of Al is defined as an “Al concentrated region”,

the primary coating satisfies the conditions of

(1) Number density D3 of Al concentrated regions: 0.015 to 0.150/μm²,

(2) (Area S5 of regions which is anchoring oxide layer regions and is also Al concentrated regions)/(area S3 of Al concentrated regions)≥0.30,

(3) Distance H5 of mean value of heights in thickness direction of regions, which is anchoring oxide layer regions and is also AL concentrated regions, minus H0: 0.4 to 4.0 μm,

(4) (Perimeter L5 of regions which is anchoring oxide layer regions and is also Al concentrated regions)/(observed area S0): 0.020 to 0.500 μm/μm²,

(5) (Area S1 of anchoring oxide layer regions)/(observed area S0)≥0.15.